Question: Given $ \overrightarrow{PQ}\perp\overrightarrow{PS}$, $ m \angle QPR = 7x + 34$, and $ m \angle RPS = 2x + 47$, find $m\angle RPS$. $P$ $Q$ $S$ $R$
Answer: From the diagram, we see that together ${\angle QPR}$ and ${\angle RPS}$ form ${\angle QPS}$ , so $ {m\angle QPR} + {m\angle RPS} = {m\angle QPS}$ Since we are given that $\overrightarrow{PQ}\perp\overrightarrow{PS}$ , we know ${m\angle QPS = 90}$ Substitute in the expressions that were given for each measure: $ {7x + 34} + {2x + 47} = {90}$ Combine like terms: $ 9x + 81 = 90$ Subtract $81$ from both sides: $ 9x = 9$ Divide both sides by $9$ to find $x$ $ x = 1$ Substitute $1$ for $x$ in the expression that was given for $m\angle RPS$ $ m\angle RPS = 2({1}) + 47$ Simplify: $ {m\angle RPS = 2 + 47}$ So ${m\angle RPS = 49}$.